Advertisement

Advertisement

BIG PHYSICS, BIG QUESTIONS –

Forum: On being a bit green – A couple of suggestions for saving the Earth

By JOHN EMSLEY

‘FIFTY ways to be a real greenie,’ said an article in my daughter’s
magazine, and it gave 50 simple changes she could make to her lifestyle
which would help to save Mother Earth. Never one to shun a lost cause, I
read on. Here are some of the touching ways she was told could take the
pressure off our fragile planet: offer her friends herbal tea instead of
ordinary tea; eat apples whole, including the core; walk more briskly; discuss
TV programmes; and, most inconsequential of all, put out left-over pet food
for hedgehogs.

Of course, not all the tips were such gems of innocent delight. Some
did make scientific sense, at least if you believe in the greenhouse threat
from carbon dioxide. Because the increase in carbon dioxide comes from burning
gas, oil and coal, if we reduce our energy demands we will reduce the amount
of CO2 in the atmosphere. Tips such as: use a pressure cooker;
have a shower instead of a bath; travel on public transport; and buy low
wattage light bulbs all made sense. But these suggestions were in a minority.

And there’s the rub. Scientists who advance theories which predict catastrophes
must be prepared to offer advice that will enable not only governments,
but you and me, to take positive action, however marginal. Scientists cannot
map out the broad expanses and leave the nonscientists to fill in the detail.
In that way we end up with people believing that they can help to save the
planet by giving herbal tea to hedgehogs.

The trouble with offering advice is that it has to stick in the mind.
Of the 50 tips offered in the magazine, the most unexpected were the easiest
to remember, and even those I may unwittingly get slightly wrong. It is
easy to think up ways of cutting our demand for energy and reducing waste.
Stay at home on Saturdays and potter in the garden, spend Sundays in bed
with a good book, and find a second use for everything. Such easy commandments
are too easy to forget and may be hard to stick to anyway. In any event
‘Potter in the garden more often!’ is hardly a rallying cry to stir the
uncommitted.

Advertisement

No, what we need are green rules that meet two requirements. First,
they must be unforgettable, and second they must require little effort to
keep. In this spirit I propose two green tips of my own. The first is memorable
because it appears rather bizarre – ‘Ban garden patios!’; the second because
it seems the antithesis of the green movement – ‘Ban biodegradable plastics!’
However, both will be of far more benefit to the Earth than catching hedgehogs
with herbal tea.

So what is anti-green about a garden patio, and especially the kind
that is screened from next door’s view by ornamental building blocks? The
answer is concrete, or rather the cement from which it is made. Concrete
not only chokes our towns and cities, but its manufacture is choking the
atmosphere. The demand for cement now runs at about 800 million tons per
year worldwide.

To produce this gigantic amount means heating limestone and clay at
temperatures up to 1450 Degree C. Not only does this heating use fossil
fuels, which produce CO2, but the actual process of cement-making
drives off enormous quantities of the same gas. This happens as the limestone,
CaCO3, is converted to calcium oxide, Ca0, and its dreaded CO2
escapes. Heat 1000 kilograms of limestone and you release 440kg of CO2.

Assuming that 500 million tonnes of limestone are used for this purpose
each year, then more than 220 million tonnes of CO2 are spewing
into the atmosphere from cement works alone. This represents more than 44
kilograms, or a million litres, of this gas for every inhabitant on the
planet every year. No amount of pressure-cooking hedgehogs is ever going
to compensate for this. However, if we deny ourselves a concrete patio and
fancy walling we can reduce CO2 emissions without lifting a finger.
And this is a sacrifice we can make year after year, until the greenhouse
scare is over.

My second tip is to ban biodegradable packaging. Now this rally cry
again makes fairly light demands on your time, but it might make you unpopular
among environmentalists who have not properly thought out what biodegradability
really means. When you go shopping, you must ask for polythene shopping
bags and search out food wrapped in cling-film.

Remember, if a plastic is biodegradable it will, like paper, be attacked
by bacteria, and those little beasts will eventually turn the carbon it
contains into either carbon dioxide or methane, both of which are greenhouse
gases. Not so with polythene. And the energy used to produce a polythene
shopping bag is no more than that for a paper carrier. Polythene was specially
designed by chemists so that it would last a long time; and, even though
it is 85-per-cent carbon, it defeats all attempts by bacteria to break it
down. Its carbon will remain safely locked away for ever, if only we treat
it right. Polythene can be recycled, and when it has been through a few
uses such as cling-film, Tupperware, shower curtains and garden gnomes,
we can finally melt it down and use it as tar for roads.

So there you have it. Forget about saving the Earth by feeding boiled
hedgehogs to your pets. Go for scientifically sounder goals and do both
the planet, and the hedgehogs, a favour.